#include<iostream>

using namespace std;

class null_test {

public:
	void sk()
	{
		if (this == NULL)
		{
			return;
		}
		num = 10;
	}
	int num;
};

int main()
{
	null_test *p = NULL;
	p->sk();
	//p->num = 10;
	//cout << p->num;

	system("pause");
	return 0;
}